Excavator tooth assemblies mounted to the digging edge of excavator buckets and the like generally comprise a replaceable digging tooth, an adaptor body and an adaptor nose which is secured by welding or the like to the digging edge of a bucket or the like. The tooth generally has a socket-like recess at its rear end to receivably locate a front spigot portion of the adaptor nose and a removable locking pin is generally employed to releasably secure the tooth on the adaptor.
In use, excavator teeth are subjected to extensive load forces along a longitudinal axis of a tooth as well as in vertical and transverse directions. A snug fit is required between the digging point and the front portion of the adaptor and also between the adaptor socket and the nose spigot portion and their respective mounting pins to avoid premature wear between the components. As the various components wear, the locking pins can loosen thereby increasing the risk of loss of a digging point or an entire adaptor/tooth combination. This necessitates considerable downtime to replace the lost wear members and where items such as locking pins are not recovered, these can cause damage and/or further downtime in downstream operations such as ore crushing and the like.
The greatest loads experienced by excavator tooth assemblies are vertical loads which tend to generate large moment forces capable of rotating a tooth off the front of an adaptor and/or rotating the adaptor off the adaptor nose. In addition, twisting or “yaw” loads are frequently imposed on such tooth assemblies.
Despite many prior art attempts to improve the mounting of a wear member to a nose of an excavator, most of these proposals suffer from one or more deficiencies.
While generally satisfactory for their intended purpose, the prior art all suffer from one or more shortcomings or disadvantages in terms of inadequate resistance to rotation of a tooth off a nose or an adaptor under the influence of vertical loads applying a rotational moment to the tooth, a predisposition to premature wear, difficulties in retention of the teeth on noses or adaptors, inadequate locking systems and unduly complicated configurations giving rise to increased fabrication costs.